Multiple piston pump apparatus

ABSTRACT

A multiple piston pump apparatus having a plurality of pump cylinders and pump pistons in the cylinders operated in successive preselected phase relation to deliver fluid from the several cylinders to a common utilization device, and in which provision is made for relieving the output of one or more of the pump cylinders as the delivery pressure builds up, to thereby deliver the combined output from the pump cylinders to the utilization device at low pressures and to reduce the volume output of the pump and hence the power required to drive the pump at relatively higher delivery pressures.

[451 Aug.8, 1972 FOREIGN PATENTS OR APPLICATIONS 258,404 11/1948 Switzerland..............4l7/288 810,778 3/1956 Great Britain.............4l7/286 Primary Examiner-William L. Freeh Attorney-McCanna, Morsbach, Pillote & Muir [57] ABSTRACT A multiple piston pump apparatus having a plurality of pump cylinders and pump pistons in the cylinders operated in successive preselected phase relation to deliver fluid from the several cylinders to a common utilization device, and in which provision is made for relieving the output of one or more of the pump cylin- Donald L. Yarger, 5118 Timber Lane, Woodstock, 111. 60098 Aug. 31, 1970 US. Cl....................................4l7/270, 417/288 [51] Int. Cl. 27/04, F04b 1/08 417/273, 286, 288, 270

References Cited UNITED STATES PATENTS United States Patent Yarger [54] MULTIPLE PISTON PUMP APPARATUS [72] Inventor:

[22] Filed:

[211 App]. No.: 68,258

[58] Field of ysnvrr. r 86 w e m wh r g e w oi hfir o cmmlvu D- e ,m m .w PU mm 3 w a Se r. W M t m u m m a g b 0 MP m w n U U 8 M 3 wW m mm pomwmm f w s; .m wm w 4 n n 1 e m o d r N/ 10 8 m e m t w $425k mmww w.. flewkhe v" wm u.w ed 0% W ddttrd 30003800900 7877008600 22222222 77777777 llllllll 444 .4 .4 n u Tmm r rl m m m e m m m w w w m m m u o e o 0 d FTfiMTGLB ID 4 18 208 Jfl64M364 99999999 HHHH UWWW6674 88000 842 003546947 ,3 ,3 ,3 65507 50 90254644 fi mR vl fl v w 22 22 22 MULTIPLE PISTON PUMP APPARATUS BACKGROUND OF THE INVENTION In some hydraulic apparatus, the load on the hydraulic apparatus changes during its cycle of operation from a light load to a relatively heavy load. In other hydraulic apparatus, the load on the hydraulic apparatus may vary due to unusual or above normal peak loading on the hydraulically operated equipment. It is heretofore been proposed, for example as disclosed in US. Pat. No. 2,366,388 and 2,377,556 to utilize several different pumps, usually of the rotary gear 'or vane type, arranged in a system to deliver large volumes of fluid at low pressures and relatively smaller volumes of fluid at high pressures. It was a common practice in such multiple pump systems to arrange the multiple pumps so as to operate in parallel when the delivery pressure is low and to thereafter connect the pumps in series so that the output of one pump is delivered to the input of a second pump to reduce the pressure difi'erential across each pump stage.

SUMMARY OF THE INVENTION The present invention relates to a multiple piston type pump having a plurality of pump cylinders and pump pistons in the cylinders operated in successive preselected phase relation. The discharge passages from the several cylinders are normally connected to a common delivery line leading to the fluid utilization device for a relatively high volume flow. Provision is made for relieving the output of some of the pump pistons as the delivery pressure builds up so as to reduce the number of pumping pistons which are effective to deliver fluid to the utilization device, and thereby minimize the peak power requirements for driving the pump. When the output of any one of the pump cylinders is relieved, flow from the delivery passage to that pump cylinder is automatically shut off. The valve arrangement for relieving the pump cylinders is advantageously so arranged as to unload that cylinder when the delivery pressure reaches the preset relief pressure for that cylinder.

An important object of this invention is to provide a multiple piston pump apparatus which is adapted to deliver high volume at low pressures and relatively lower volume at high pressures to reduce the overall power requirements necessary for driving the pump.

A more particular object of this invention is to provide a multiple piston pump in which the output of the several pump cylinders is successively relieved as the delivery pressure increases to thereby successively reduce the number of pistons in the pump which are effective in delivering fluid pressure, as the delivery pressure increases.

Yet another object of this invention is to provide a multiple piston pump in accordance with the foregoing object having an improved valve arrangement for unloading the pump cylinder, when the delivery pressure reaches the relief pressure preset for that pump cylinder.

These, together with other objects and advantages of this invention will be more readily understood by reference to the following detailed description when taken in connection with the accompanying drawings wherein:

FIG. I is a sectional view through a multiple piston pump apparatus embodying the present invention; and

FIG. 2 is a transverse sectional view taken on the plane 2 -2 of FIG. 1.

Referring now more specifically to the accompanying drawings, the pump apparatus in general includes a casing 10 having a plurality of pump cylinders 11 therein, pump pistons 12 slidably mounted at each of the cylinders, and a cam means 16 for reciprocating the pistons in successive preselected phase relation. In the embodiment shown, a three piston type pump is illustrated, it being understood that a greater number of cylinders and pistons can be utilized if desired in practicing the present invention. The pump may be of the radial or axial piston type wherein the pump cylinders and pistons are circumferentially spaced apart for operation by the cam in preselected phase relation. In the embodiment illustrated, the pump is of the radial piston type and the pump cylinders 11 are formed in cartridges mounted in bores in the pump casing, as more fully disclosed in my copending application for US. letters Pat. Ser. No. 58,529 filed July 27, 1970, entitled Piston Type Pump." In general, the pump includes a plurality of circumferentially spaced bores, herein shown three in number and designated 13a, 13b and 13c, cartridges l4a-l4c removably mounted in the bores as by threaded engagement therewith, and sleeve liners 15 in the cartridges defining the pump cylinders lla11c. Pump pistons l2a-12c are slidably mounted in the pump cylinders Ila-11c respectively and are cyclically reciprocated in preselected phase relation by a cam 16. As best shown in FIG. 2, the cam 16 is mounted on a shaft 17 ratatably supported by bearings 18 and 19 on the pump casing, and the shaft is adapted to be driven by a motor diagrammatically indicated at 21.

Fluid is supplied to the pump from a supply source such as a reservoir diagrammatically shown at 28 in FIGS. 1 and 2, trough a fluid supply line 29 connected to an inlet chamber 31 in the pump. The pistons l2a12 in the respective cylinders lla-l 1c define motive chambers 32a-32c between the pistons and the cylinder heads. Inlet passage means 33a-33c and inlet valve means 34a-34c are provided to supply fluid to the motive chamber during the intake stroke of the respective piston, that is during movement of the piston relative to the cylinder in a direction to expand the respective motive chamber. In the form shown, the inlet valve means are in the form of check valves conveniently located in the pistons, and the inlet passage means are also located in the pistons and extend from the respective motive chamber to the fluid supply chamber 31. Fluid discharge passage means 36a-36c and fluid discharge valve means 37a-37c are provided for each motive chamber to allow delivery of fluid from each motive chamber during the discharge stroke of the respective piston, that is during movement of the piston in a direction to contract the respective motive chamber. In the embodiment shown, the discharge valve means 37a-37c are in the form of check valves and the discharge passages 3611-360 are formed in the cartridges to communicate at one end with the respective motive chamber and have lateral passage portions 36 that communicate at their outer ends with a respective annular distribution channel 38a-38c formed between the cartridge and the bores in the pump casing. As is well known, the inlet check valves 34a-34c are arranged to close in a direction opposite the direction of fluid flow from the supply chamber 31 through the inlet passage into the motive chamber, and the discharge check valves 37a-37c are arranged to close in a direction opposite the direction of flow of fluid from the respective motive chamber. Springs 39 are provided for yieldably urging the outlet check valves to a closed position with a relatively light force. The inlet check valves can be urged to a closed position by the fluid pressure in the respective motive chamber or by a suitable check valve spring (not shown).

The discharge passages 36a-36c from the several motive chambers 32a-32c respectively are connected to a common delivery passage 50 so as to supply fluid from the several motive chambers to a fluid utilization device 51. While the utilization device can be of different forms, it is herein diagrammatically shown as a cylinder having a movable piston therein which is reversibly operated under the control of a flow reversing valve 52. As shown, the discharge chamber 38a of motive chamber 32a is connected through cored passages 53a and 53b in the valve casing to the discharge chamber 380 and, similarly, the discharge chamber 38b of motive chamber 32b is connected through cored passages 53c and 53d in the valve casing to the discharge chamber 380. The delivery passage 50 is in open communication with the discharge camber 38c and in the form shown, is connected through a fitting 55 on the cartridge 14c and through the lateral discharge passage portions 36' in the cartridge 14c with the discharge camber 38c.

The pump is arranged so as to deliver fluid from the several motive chambers 32a-32c to the delivery passage 50 leading to the utilization device 51 when the pressure in the delivery passage is relatively low to provide high volume flow at low pressures and provision is made for relieving the fluid pressure discharge from one or more of the motive chambers as the pressure in the delivery passage builds up to reduce the volume output of the pump and hence the power required to drive the pump at relatively higher pressures. At best shown in FIG. 1, a first valve assembly 61 is provided for controlling the flow of fluid between the discharge passage 36a associated with one motive chamber 32a, the delivery passage 50, and a first relief passage 62 that leads back to the fluid supply such as the inlet chamber 31. The valve assembly 61 is conveniently of the cartridge type including a body 63 which is mounted in a bore 64 in the valve casing, as by threaded engagement therewith as indicated at 65. The valve body 63 has an axial passage 66 and is counterbored at one end to form a valve chamber 67 and a seat 68 between the chamber 67 and the bore 66. The body 63 is also counterbored at its other end to provide a valve camber 69 and a second seat 71 between the chamber 69 and the passage 62. A relief valve member 72 is disposed in the chamber 69 and is yieldably urged as by a relief valve spring 73 to a closed position against the seat 71. As shown, the spring 73 is interposed between the valve member 72 and an adjustable plug 74 to allow adjustment of the spring pressure applied to the valve member 72 to thereby adjust the relief pressure. A delivery valve member 78, conveniently in the form of a ball valve, is disposed in valve chamber 67 and is movable to a position in engagement with seat 68 to block flow therethrough.

The passage 66 in the valve body 63 communicates through passages 81 and groove 82 with the passage 53a leading to the discharge chamber 380 and discharge passage 36a. Valve chamber 67 in the body 63 communicates through passage 53b, discharge camber 13c and lateral passage portions 36' in the cartridge 14c with the delivery line 50. Valve chamber 69 in the valve body 63 communicates through lateral passages 83 and groove 84 with the relief passage 62. Thus, fluid discharged from motive chamber 32a normally flows through discharge passage 36a, discharge chamber 380, passage 53a and through passages 81, past seat 68 and through passage 53b to the delivery passage 50. As will be seen, valve 78 is arranged to open for flow from the passage 66 to the delivery passage. Relief valve 72 is normally urged to its closed position blocking flow to the relief passage until the pressure in the delivery passage reaches a preselected value sufficient to overcome the pressure of spring 73. At that time, the relief valve opens to allow flow from the passage 53a through the relief passage 62. At that time, the pressure in the passage 66 drops below the pressure in the delivery passage and the delivery valve 78 is thereby pressure urged to a position against seat 68 to block flow from the delivery line back to the discharge passage of chamber 32a. lf desired, a lightweight spring can be provided to aid in moving the valve 78 to its closed position. The valve assembly is advantageously arranged so as to unload the motive chamber associated with the valve as soon as the delivery pressure reaches the preset relief pressure of the spring 73. For this purpose, a member 88 is interposed between the valve member 78 and the relief valve member 72 so that the fluid pressure acting on the delivery valve member 78, when the latter is closed, holds the associated relief valve member 72 in its open position to thereby provide relatively free discharge of fluid from passage 530 back through the relief passage.

A second valve assembly 61b is advantageously provided for controlling flow from the motive chamber 32b to the delivery passage 50 and a relief passage. The valve assembly 61b is conveniently constructed in the same manner as the valve 61 and like numerals followed by the subscript prime (b) are used to designate corresponding parts. Thus, valve assembly 61b also includes a relief valve 72b for controlling flow of fluid from discharge passage 530 back trough a relief passage 62b, and a delivery valve 78b for controlling flow of fluid between the passage 53d leading to the delivery passage 50 and the passage 530 leading to motive chamber 32b. Relief valve 72b is also yieldably urged as by a spring 73b to a closed position, the spring pressure being adjustable as by an adjustable plug 74b. The relief pressure on relief valve 73b can be adjusted as to relieve the discharge from the motive chamber 32b at a pressure relatively different from that of relief valve 72 and may, for example, be a relatively higher pressure so that the motive chambers 32a and 32b are successively relieved as the pressure builds up. Valve 78b is arranged to close when the relief valve 72b opens to block flow from the delivery passage back to the motive chamber and a member 88b is provided to hold the relief valve in its open position while the delivery valve 78b is closed so as to unload motive chamber 32b.

A relief valve is also provided for the delivery passage to limit the maximum pressure in the delivery line 50. As shown in FIG. 2, this relief valve 91 is conveniently located in the pump casing and includes a relief passage portion 920 communicating with the chamber 130; a relief valve chamber 93, and a relief passage portion 92b extending from the valve chamber 93 back to the fluid supply such as the chamber 31. A relief valve seat 94 is provided between the chamber 93 and the relief passage portions 920 and 92b and a relief valve member 95 is mounted in the chamber and yieldably urged as by a relief spring 96 to its closed position. An adjustable plug 97 is provided for adjusting the relief pressure applied to valve 95. Plug 97 is adjusted so as to relieve at a somewhat higher pressure than either relief valve 72 or 72b.

From the foregoing it is thought that the construction and operation of the pump apparatus will be readily understood. The pump drive cam 16 driven by the motor 21 operates to cyclically reciprocate the pistons 120-12 in preselected phase relation and the motive chambers 32a-32c associated with the several pump pistons are arranged so as to deliver their combined discharges to the common delivery passage 50 leading to the fluid utilization device 51, when the pressure in the delivery passage is below a preselected value determined by the setting of relief valves such as 72 and 72b. When the pressure in the delivery passage reaches the preset relief pressure for relief valve 72, relief valve 72 opens and delivery valve 78 closes to thereby bypass the fluid discharged from chamber 32a back through the relief passage 62. Closing of delivery valve 78 prevents flow of fluid from the delivery passage back through the relief passage or to the discharge passage associated with chamber 32a and also holds the relief valve 72 in its open position to unload the motive chamber 320. In the three piston pump shown, it is contemplated that a second one of the motive chambers be relieved at a relatively high pressure and that relief valve 72b be set to operate in a relief pressure somewhat higher than valve 72 and below the delivery line relief pressure determined by relief valve 95. Accordingly, after relief valve 72 opens, fluid will continue to be delivered from motive chambers 32b and 320 to the delivery line 50 until the pressure in the delivery line reaches the relatively higher relief pressure set for valve 72b. At that time, relief valve 72b opens to bypass the fluid discharged from motive chamber 32b back to the relief passage and delivery passage 50 and to also hold the relief valve 72b open. Motive chamber 320 continues to delivery fluid under pressure to the delivery line 50 to thereby enable delivery of fluid at a relatively high pressure but reduced volume so as to minimize the power requirements necessary for achieving a certain maximum pres sure. For example, in the three piston pump shown, the relief valves 72 and 72b can be preset so as to relieve at respectively and of the maximum discharge pressure required and under these circumstances, the horsepower requirements of the motor 21 will be only approximately A of that which would be required if all three pistons were effected to deliver fluid under the maximum pressure requirements of the system. As will be appreciated, the numbers of cylinders and pistons utilized can be increased from the three piston arrangements shown and may, for example, be increased to five or seven. As will be appreciated, relief of several motive chambers could be achieved at the same pressure, if a high number of pressure steps are not required.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pump apparatus comprising:

a. a multiple piston pump including casing means defining at least two pump cylinders, a pump piston slidable in each pump cylinder and defining a motive chamber therein, eccentric means for cylically reciprocating the pistons in successive preselected phase relation, fluid supply means including inlet passage means and inlet valve means operative to open to supply fluid to the motive chambers during the intake stroke of each piston, fluid discharge valve means operative to open to allow delivery of fluid from each motive chamber to the respective fluid discharge passage means during the discharge stroke of each piston, fluid delivery passage means adapted to supply fluid to a utilization device and communicating with the fluid discharge passage means associated with at least two of said motive chambers to receive fluid therefrom, a first pressure relief passage. means communicating with said fluid supply means and with a first of said fluid discharge passage means associated with a first of said motive chambers,

. a first valve means controlling flow between said first discharge passage means and said first relief passage means and said delivery passage means, said first valve means including a relief valve seat intermediate said first discharge passage means and said first relief passage means and facing in the direction of fluid flow to the first relief passage means, a relief valve member having means yieldably biasing the same toward a seated position against said relief valve seat and responsive to a first preselected fluid pressure in said first discharge passage means to unseat for flow through the relief passage means, said first valve means also including a delivery valve seat intermediate said first discharge passage means and said delivery passage means and facing in the direction of fluid flow to the delivery passage means, a delivery valve member cooperable with said delivery valve seat and operable when seated to block return flow from the delivery passage means to said first discharge passage means, and means operatively interconnecting said delivery valve member and said relief valve member for holding said relief valve member in an unseated position when said delivery valve member is seated to thereby unload said first motive chamber, and

c. at least one other valve means operative when the fluid pressure in a second of said passage means reaches a pressure substantially higher than said first preselected fluid pressure for passing fluid from the second discharge passage means back to said supply means.

2. A pump apparatus according to claim 1 wherein said relief valve seat and said delivery valve seat are disposed in axial alignment, said means for holding said relief valve member unseated comprising a rigid member extending between said relief valve member and said delivery valve member.

3. A pump apparatus according to claim 1 wherein said delivery valve member is larger than said relief 5 valve member.

4. A pump apparatus according to claim 1 wherein 5. A pump apparatus comprising:

a. a multiple piston pump including casing means having at least two pump cylinders, a pump piston slidable in each cylinder and defining a motive chamber therein, eccentric means for cylically reciprocating the pistons in successive preselected phase relation, fluid supply means including inlet passage means and inlet valve means operative to open to supply fluid to the motive chambers during the intake stroke of each piston, fluid discharge passage means and fluid discharge valve means individual to each motive chamber operative to open to allow delivery of fluid from each motive chamber to the respective fluid discharge passage means during the discharge stroke of each piston,

b. a first valve means including a valve passage means communicating intermediate its ends with a first of said discharge. passage means associated with a first of said motive chamber; a relief valve chamber at one end of the valve passage means defining a relief valve seat around one end of the valve passage means; and a delivery valve chamber at the other end of said valve passage defining a delivery valve seat around the other end of the valve passage means, a relief passage means communicating with said relief valve chamber, a fluid delivery passage adapted to supply fluid to a utilization device communicating with said delivery valve chamber and with the discharge passage means associated with at least one other motive chamber, a relief valve member in said relief valve chamber having relief spring means yieldably biasing the relief valve member to a seated position against said relief valve seat and responsive to a first preselected fluid pressure in said first discharge passage means to unseat for flow through the relief passage means, a delivery valve member in said delivery valve chamber operable when seated to block flow from the delivery passage means to said valve passage means, and means operatively interconnecting said delivery valve member and said relief valve member for holding said relief valve member in an unseated position when said delivery valve member is seated to unload said first motive chamber, and

c. at least one other valve means operative when the fluid pressure in a second of said discharge passage means reaches a pressure substantially higher than said first preselected fluid pressure for passing fluid from the second discharge passage means back to said su 1 means. 6. A pump appai a ti s according to claim 5 wherein said means interconnecting said relief valve member and said delivery valve member includes a rod extending through said valve passage means.

7. A pump apparatus according to claim 6 wherein said delivery valve member is larger than said relief valve member.

8. A pump apparatus according to claim 7 wherein said relief valve member and said delivery valve member comprise ball members. 

1. A pump apparatus comprising: a. a multiple piston pump including casing means defining at least two pump cylinders, a pump piston slidable in each pump cylinder and defining a motive chamber therein, eccentric means for cylically reciprocating the pistons in successive preselected phase relation, fluid supply means including inlet passage means and inlet valve means operative to open to supply fluid to the motive chambers during the intake stroke of each piston, fluid discharge valve means operative to open to allow delivery of fluid from each motive chamber to the respective fluid discharge passage means during the discharge stroke of each piston, fluid delivery passage means adapted to supply fluiD to a utilization device and communicating with the fluid discharge passage means associated with at least two of said motive chambers to receive fluid therefrom, a first pressure relief passage means communicating with said fluid supply means and with a first of said fluid discharge passage means associated with a first of said motive chambers, b. a first valve means controlling flow between said first discharge passage means and said first relief passage means and said delivery passage means, said first valve means including a relief valve seat intermediate said first discharge passage means and said first relief passage means and facing in the direction of fluid flow to the first relief passage means, a relief valve member having means yieldably biasing the same toward a seated position against said relief valve seat and responsive to a first preselected fluid pressure in said first discharge passage means to unseat for flow through the relief passage means, said first valve means also including a delivery valve seat intermediate said first discharge passage means and said delivery passage means and facing in the direction of fluid flow to the delivery passage means, a delivery valve member cooperable with said delivery valve seat and operable when seated to block return flow from the delivery passage means to said first discharge passage means, and means operatively interconnecting said delivery valve member and said relief valve member for holding said relief valve member in an unseated position when said delivery valve member is seated to thereby unload said first motive chamber, and c. at least one other valve means operative when the fluid pressure in a second of said passage means reaches a pressure substantially higher than said first preselected fluid pressure for passing fluid from the second discharge passage means back to said supply means.
 2. A pump apparatus according to claim 1 wherein said relief valve seat and said delivery valve seat are disposed in axial alignment, said means for holding said relief valve member unseated comprising a rigid member extending between said relief valve member and said delivery valve member.
 3. A pump apparatus according to claim 1 wherein said delivery valve member is larger than said relief valve member.
 4. A pump apparatus according to claim 1 wherein said first valve means including said first relief valve seat and first relief valve member and said first delivery valve seat and first delivery member are formed in a cartridge body removable as a unit from said casing means.
 5. A pump apparatus comprising: a. a multiple piston pump including casing means having at least two pump cylinders, a pump piston slidable in each cylinder and defining a motive chamber therein, eccentric means for cylically reciprocating the pistons in successive preselected phase relation, fluid supply means including inlet passage means and inlet valve means operative to open to supply fluid to the motive chambers during the intake stroke of each piston, fluid discharge passage means and fluid discharge valve means individual to each motive chamber operative to open to allow delivery of fluid from each motive chamber to the respective fluid discharge passage means during the discharge stroke of each piston, b. a first valve means including a valve passage means communicating intermediate its ends with a first of said discharge passage means associated with a first of said motive chamber; a relief valve chamber at one end of the valve passage means defining a relief valve seat around one end of the valve passage means; and a delivery valve chamber at the other end of said valve passage defining a delivery valve seat around the other end of the valve passage means, a relief passage means communicating with said relief valve chamber, a fluid delivery passage adapted to supply fluid to a utilization device communicating with said delivery valve chamber and with the discharge passage means associated with at least one other motive chamber, a relief valve member in said relief valve chamber having relief spring means yieldably biasing the relief valve member to a seated position against said relief valve seat and responsive to a first preselected fluid pressure in said first discharge passage means to unseat for flow through the relief passage means, a delivery valve member in said delivery valve chamber operable when seated to block flow from the delivery passage means to said valve passage means, and means operatively interconnecting said delivery valve member and said relief valve member for holding said relief valve member in an unseated position when said delivery valve member is seated to unload said first motive chamber, and c. at least one other valve means operative when the fluid pressure in a second of said discharge passage means reaches a pressure substantially higher than said first preselected fluid pressure for passing fluid from the second discharge passage means back to said supply means.
 6. A pump apparatus according to claim 5 wherein said means interconnecting said relief valve member and said delivery valve member includes a rod extending through said valve passage means.
 7. A pump apparatus according to claim 6 wherein said delivery valve member is larger than said relief valve member.
 8. A pump apparatus according to claim 7 wherein said relief valve member and said delivery valve member comprise ball members. 